How to encrypt your photos on Facebook, Twitter

Smartphones and mobile apps have made sharing photos faster and easier than ever, but privacy has become a growing concern.

Secret.li, an iPhone app, lets users take a photo with their iPhone’s camera and post it to Facebook knowing it will be automatically deleted an hour, a day, or a week after it is posted. “Publishing is so easy but privacy is so obscure,” said Deepak Touwari, co-founder of Secret.li, based in Lausanne, Switzerland.

After taking a photo with the app, users can decide who they want to share it with and for how long. Recipients will see a scrambled or hidden version of the photo, which they can open and view completely in the Secret.li Facebook or iPhone apps. After the photo is deleted it also disappears from Facebook and Secret.li.

Another app for iPhone and Android, called Facebook Poke – created by Facebook – allows users to send their friends messages, photos and videos and decide how long they can view it.

Spirit, a web app for Twitter released last week, lets members of the micro-blogging site add a hashtag to their tweet so it will auto-delete. Users authorize their account and add hashtags such as “#30m” or “#10d”, which will delete their tweets after 30 minutes and 10 days respectively.

Legrain, a former Twitter employee, said the motivation for the app was privacy. Part of the value of Spirit for Twitter is its ability to filter out content that loses accuracy or relevancy over time.